Rotary impact tool



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ROTARY IMPACT TOOL Filed April 1, 1955 2 Sheets-Sheet 1 FIG: 2

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y 1956 J. A. w. MADSEN 2,756,853

ROTARY IMPACT TOOL Filed. April 1, 1955 2 Sheets-Sheet 2 FIG, 4

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United States Patent "ice 2,756,853 ROTARY IMPACT TobL Jens Axel W. Madsen, Sioux City, Iowa, assignbr to Albertson & Company, Inc, Sioux City, Iowa, a corporation of Iowa Application April 1, 1955, serial No; 498,558 12 Claims. or. 192-305 This invention relates to a rotary impact tool of the type incorporating a torque release clutch in the drive between the wrench and the source of power the" "for, the clutch being automatically and periodically released and reengaged under a predetermined torque load as long as power is applied to the wrench and rhovemeri t of the wrench is sufficiently resisted to elfect the production of a series of impacts thereupon. In a form of impact wrench presently available the torque release clutch used therein is in effect a lurality of clutches and incorporates a plurality of Vgrooves 6n a common clutch driving element, a plurality of V grooves on a common clutch driven element inverted with respect to the first mentioned -grooves, and balls retained between the driving and driven V-grooveshand serving to transmit the drive therebetween. A single spring urges the driving and driven elements together, but permits a separation of these elements when the torque resistance of the driven element exceeds the torque transmitted by the balls through the spring reaction. The separation of the driving and driven elements results in the storage of energy in the Spring, the stored energy being subsequently released .to produce an impactupon the wrench driven b y the clutch. "This form of clutch, with its plurality of V-grooves, is somewhat difficult, and consequently expensive, to manufacture. M

It is an object of this invention to provide a torque release clutch for an impact wrench which is simple toj construct in that but one such clutch, in effect, is utilized for the transmission of the drive. I H a 7 As a more specific object, this invention provides a torque release clutch adapted to be eifective to release a driving force therethrough, irrespective of the direction of rotation, when a predetermined torque resistance is imposed upon the driven element of the clutch, and wherein the force imparted v between the driving anddriven elements of the clutch is transmitted through a plurality of balls, there being in effect a reservoir of balls, so that the load may be taken up successively by the balls of a series. I V u v v For another object, this invention has within itspu-rview the provision of atorque release clutch for a rotary impact tool wherein one continuous cam surface is used, the cam. surface extending around 360 relative .to-th'e clutch axis and. being constituted by pairs of right and left hand helical surfaces the ends of which are joined to form single continuoussurfaces.

These and other objects of this invention will become apparent from the following detailed description when taken together with the accompanying drawings, in which:

Fig. 1 is a; side elevation-alt View of the exterior of an impact tool of the type to" which this invention is appli cable",

Fig. 2 is a longitudinal sectional view through: the torque release clutch: of the impacttool of Fig- 1,; drawn to a larger scale than Fig.- 1 and includes portions of 2,756,853 Patented July 31, 1956 2 the adjacent mechanism of the tool which cooperate with the clutch;

Fig. 3 is a transverse sectional view through the clutch of Fig. 2, taken substantially at the position of the line 3 -3 in Fig. 2 and in the direction of the arrows, the clutch being shown in its engaged condition;

Fig. 4 is a view corresponding to Fig. 2, but showing the clutch in its released condition;

Fig. Sis a transverse sectional view through the tool of Fig. 2, taken substantially at the position of line 55 in Fig. 2 and in the direction of the arrows; and

Fig. 6 is a transverse sectional view of the clutch parts taken substantially at the location of a line 6-6 in Fig. 2 and in the direction indicated by arrows.

Referring now to the drawings for a detailed description of the preferred embodiment of the invention depicted therein, and particularly to Fig. 1, the illustrated impact tool has a housing 10 which encloses an electric motor of suitable construction, said housing 10 having appended thereto a handle 11 from which a movable v trigger 12 projects for effecting manual actuation of an on and on switch (not shown) for controlling the operation of the motor. A brush housing 13 for the motor is attached to one end of the housing 10, as shown in Fig. 1, and secured to and extending from the other end of the housing 10 is a housing 14 which encloses the torquer elease clutch and associated mechanism by which an impact is periodically imparted to a wrench drive shaft 15 of the tool. I

Referring now to Fig. 2, for the details of constructionofrny driving mechanism and torque release clutch, a drive shaft 16 of the motor has a plurality of teeth out in the operative end thereof to serve as a sun gear 17 of a planetary gear set. The teeth of the sun gear 17 mesh with a pair of diametrically opposed planet pinions 18, both of which mesh with an internally toothed ring gear 19 which constitutes the third element of the planeta-ry gear set.

Planetpinions 18 are rotatably mounted in pinion shafts 20 which, in turn, are secured to a carrier 21. A central flange 22 on the pinion carrier 21 is supported for rotation in a partition plate 23 through an anti-frict-ion bearing 24. The pinion carrier also has on its opposite end a shaft portion 25 (see Fig. 4) which is pilotedina recess 26 in the inner end of the shaft i5; the shaft 15. being, in turn, rotatab'ly mounted in a sleeve bearing 27 which is fixedly mounted in an opening 28 in a tapered end portion 29 of the housing 14. The housing 14 'an d the partition plate 23 are r'emovahly secured to the motor housing 10 by fastening means such as a plurality of screws 39 extending through an attaching flange 31 on end of housing 14 opposite the tapered end portion 29'.

Arec'ss 32 is provided on the interior of the flange 31 to re eive the ring ear 19. In the structure disclosed, the tightening of screws 30 effects a clamping of the r'irig gear 19 between the housing 14 and the partition plate 23, and the latter is, in turn, clamped against housing 1 0 To this end, flange 31 is made short enough in axial length to avoid contact of the adjacent end thereof with an outer flange portion 23a on the partition plate" 23, which flange portion extends between the flange 3'1 and the housing 10.

It may be observed that with ring gear 19 held station'ary and sun gear 17 driven by the motor in housing 10; a speed reduction will be effected between motor shaft 16 and carrier 21, and at the same time a corresponding torque multiplication will be produced for driving the earrier'zl.

Driving force" is transmitted from carrier 2-1 to the shaft 15 through a torque responsive mechanism ifidi 3 cated generaly at 33 and an impact creating mechanism shown generally at 34.

The torque responsive mechanism includes a sleeve 35 (Fig. 4) fitting over a stepped portion 36 on carrier 21. Sleeve 35 is driven from the stepped portion 36 of the carrier by one or more steel balls 37 which are received in dimples 38 in the surface of the stepped portion 36 and extend into recesses 39 in the sleeve 35. A radially disposed surface orshoulder 40 is provided on the sleeve 35 and serves as atrack for a plurality of torque transmitting steel balls 41. Surface 46 is in the form of left and right-hand helices joined together at a low point 42 and at a high point 43 (Fig. 2), the surface being continuous and smoothly rounded at the low and high points. Immediately adjacent the surface 40 is a shallow peripheral groove 44 which follows the contour of the surface 40 and in which the balls 41 are disposed. It is contemplated that the balls 41 shall not extend radially beyond the outer surface 45 of sleeve 35.

Telescoped over an end portion of the sleeve 35 is a driven element 46 of clutch 33. The driven element 46 is comprised of a second sleeve having one end surface 47 provided with a pair of left and right-hand helical surfaces which meet at a high point 48 and at a low point 49, the terms high and low being taken with reference to the end of the sleeve opposite the sleeve 35, as shown in Figs. 2 and 4. The pitch of the two helical surfaces between the high and low points 48 and 49 is substantially the same as the pitch of the helical surfaces between the high and low points 43 and 42 of sleeve 35, so that when sleeves 35 and 46 are so related as to have the high point of one angularly aligned with the low point of the other a groove of substantially uniform width is formed, in which balls 41 are retained.

Sleeve 46 is retained within a sleeve-shaped hammer 50 on the central interior of which is an integral and inwardly extending flange 51 which acts, on one side, as an abutment for sleeve 46 and, on the other, as an abutment for a spring 52 surrounding an adjacent portion of the carrier 21. The end of the spring 52 opposite the flange 51 bears against the inwardly flanged end 53 of a sleeve 54 which surrounds a portion of the spring 52. The sleeve 54 also serves to center, and to provide a large bearing area for, the right hand end (Fig. 4) of the hammer 50 relative to the carrier 21. Relative rotation between the hammer t) and the carrier 21 and the absorption of end thrust are provided for by a thrust bearing 55.

Rotational driving force is transmitted from the sleeve 46 to the hammer 50 by a pair of lugs 56 (Fig. 3) formed integrally on one end of the sleeve 46, as shown in Figs. 2 and 3, which lugs extend into aligned recesses 57 in the flange 51 of hammer 50. The end of the hammer 50 opposite that in which the sleeve 54 is inserted extends over the surface 45 of the sleeve 35 and in close proximity thereto, so that balls 41 are retained in shallow groove 44 by an inner surface 58 of hammer 50. Thus, even though sleeves 35 and 46 may be rotated relative to one other in a manner to cause a separation or divergence of the surface 40 and end 47, the balls 41 nevertheless will be constrained to move in groove 44 by the hammer 50.

The impact creating mechanism 34 includes a pair of anvils 59 which extend axially from a flanged end 60 of shaft 15. Said anvils 59 as viewed in Fig. 6 are arcuate in form and extend over substantially 45 of the circumference of the said flanged end piece 60. The end of hammer 50 adjacent the anvils 59 is similarly formed with axial-1y extending lugs 61 which are circumferentially aligned with the anvils 59 and are urged into the spaces between the anvils by the spring 52 acting against the flange 51 in the hammer 50.

Driven element 46 has an inwardly extending flange 62 at one end which overlies the adjacent end of the sleeve 35, so that the flange 62 may contact the end of the sleeve 35 in an extreme case and limit the axial movement of the driven element 46 toward the balls 41. It is contemplated, however, that when driven element 46 is in its extreme position of movement toward the sleeve 35, it will contact the balls 41 rather than flange 62. Spring 52 will normally hold the hammer 50 and the driven element 46 with the balls 41 contacting both, and with flange 62 slightly spaced from the end of the sleeve 35. In this position, the hammer lugs 61 are disposed between anvils 59 and approximately of lost motion is available between the lugs 61 and anvils 59 to provide for impact of the lugs against the anvils.

In operation, assuming that the carrier 21 is being rotated by the motor and that shaft 15 is connected to a suitable wrench 63, as shown in Fig. 2, which wrench is, in turn, fitted over the head 64 of a bolt 65 to be tightened in a threaded opening 66, the torque responsive mechanism 33 and the impact creating mechanism 34 will occupy substantially the positions shown in Fig. 2, while the bolt is turning with relative freedom in the threaded opening 66. When the torque required to turn the bolt, as when the bolt is being finally tightened, reaches a limiting amount, however, the resistance to turning efiects relative rotation between the sleeve 35 and driven element 46, thereby causing balls 41 to ride along the end 47 to push that end axially away from the end 40 of the sleeve 35. Such axial movement continues until the lugs 61 are no longer in axial alignment with the anvils 59, whereupon the torque load is instantly released from hammer 50, and said hammer is then turned, with the lugs 61 riding over the ends of the anvils 59 until they are over the spaces between the anvils. At this point, the spring 52 pushes the hammer 50 and the associated driven element 46 axially along the carrier 21 to a position such that the lugs 61 are aligned for contact with the anvils 59, the rotational movement of hammer 50 being accelerated in the meantime, and a sharp blow will be imparted to the anvils 59. If the torque load is still suflicient to effect compression of the spring 52 as a result of the camming action of the balls 41 between the end surfaces 40 and 47, the withdrawal of hammer 50 and reapplication of the impact of the lugs 61 against the anvils 59 will be repeated, thereby imparting a continuing series of blows to the anvils which are transmitted through wrench 63 to the bolt head 64 to turn said bolt.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a rotary impact tool, a rotatably supported anvil, a hollow cylindrical hammer having portions adapted to engage the anvil, said anvil and hammer being coaxial and relatively reciprocable axially of the anvil, a drive shaft, and torque responsive clutch means disposed within the hammer and adapted to effect connection of the drive shaft to the hammer to drive said hammer, said clutch means comprising a driving sleeve, means connecting the driving sleeve to the drive shaft for rotation therewith, a driven clutch element within the hammer, interfitting means for connecting the hammer for rotation with the driven element, axially opposed and substantially identical parallel surfaces on the clutch driving sleeve and driven element, said surfaces being inclined relative to the axis of the drive shaft, a plurality of balls adapted to transmit axial thrust developed between the opposed surfaces, and resilient means urging the clutch driving sleeve and driven element together.

2. In a rotary impact tool, a rotary anvil, a hollow cylindrical hammer having portions adapted to engage the anvil, said anvil and hammer being axially reciprecablerelativeto one another for effecting engagement and disengagement between the anvil and said portions of the hammer, a drive shaft, and torque responsive clutch means disposed within the hammer and adapted to connect the drive shaft to the hammer to drive saidhainmer, said clutch means comprising a driving sleeve, means for conhecting the driving sleeve to the drive shaft for rotation therewith, a driven clutch element telescopically disposed with respect to the driving sleeve, a radially inwardly disposed flange on the hammer, interfitting means on the flange and driven clutch element to transmit driving force from the-clutch to the hammer, axially opposed and substantially identical helical surfaces on the clutch driving sleeve and driven element, a plurality of balls interposed between the opposed helical surfaces and adapted to transmit a driving force therebetween, and resilient means urging the clutch driving sleeve and driven element together.

3. In a rotary impact tool, a rotary anvil, a hollow cylindrical hammer having portions adapted to engage the anvil, said anvil and hammer being axially reciprocable relative to one another for effecting engagement and disengagement between said anvil and said portions of the hammer, a drive shaft, and torque responsive clutch means disposed within the hammer and adapted to conmeet the drive shaft to the hammer, said clutch means comprising a driving sleeve, means-for connectingthe driving sleeve to the drive shaft for rotation therewith, a driven clutch element within the hammer, interfitting means on the hammer and driven element for connecting the hammer for rotation with the driven element, substantially parallel and helical radially disposed surfacesin opposed relationship to one another, one on the driving sleeve and the other on the driven clutch element, a plurality of balls interposed between the parallel surfaces and adapted to transmit a driving force therebetween, and resilient means urging the clutch driving sleeve and driven element together.

4. In a rotary impact tool, a rotary anvil, a hollow cylindrical hammer having portions normally aligned for engagement with the anvil, said anvil and hammer being axially reciprocable relative to one another for moving said portions of the hammer and said anvil to and from alignment with one another, a drive shaft, and torque responsive clutch means disposed within the hammer for providing a driving connection between the drive shaft and the hammer, said clutch means comprising a driving sleeve, means for connecting the driving sleeve to the drive shaft for rotation therewith, a driven clutch element within the hammer, interfitting parts on the hammer and driven clutch element for connecting the hammer for rotation with the driven clutch element, substantially parallel helical and radially disposed surfaces on the driving sleeve and on the driven clutch element, each such helical surface including reversely disposed helical portions, a plurality of balls interposed between the opposed surfaces for transmitting driving force therebetween, and resilient means urging the clutch driving sleeve and driven element together.

5. In a rotary impact tool, a rotary anvil, a hollow cylindrical hammer having a portion normally aligned for engagement with the anvil, said anvil and hammer being axially reciprocable relative to one another for moving said portion of the hammer and said anvil to and from alignment, a drive shaft, and torque responsive clutch means disposed within the hammer for providing a disengageable driving connection between the drive shaft to the hammer, said clutch means comprising a driving sleeve, means connecting the driving sleeve to the drive shaft for rotation therewith, a driven clutch element within the hammer, interfitting means on the hammer and driven element connecting the hammer for rotation with the driven element, two pairs of substantially parallel and helical radially disposed surfaces, one surface of each pair being formed on the driving sleeve and the other surface of each pair being formed on the driven clutch element, each pair being curved in the opposite direction from. the other pair, and the ends of the pairs being joined to provide continuous surfaces on the driving sleeve and driven clutch element,- a plurality of balls interposed between the parallel surfaces for transmitting driving force therebe tween, and resilient means urging the clutch driving sleeve and driven element together.

6. A rotary impact tool as defined in claim 5, and wherein the driving sleeve has a peripheral groove adjacent the hclical surfaces thereon for receiving said balls, and wherein the hammer extends over the balls and serves to retain them in the groove while said surfaces are separated as a result of relative rotation therebetween.

7. In a rotary impact tool, a rotary anvil, a hollow cylindrical hammer having a portion normally aligned for engagement with the anvil, said anvil and hammer being axially reciprocable relative to one another for moving said portion of the hammer and said anvil from and to positions of alignment, a drive shaft, and torque responsive clutch means disposed within the hammer for providing a disengageable driving connection between the drive shaft and the hammer, said clutch means comprising a driving sleeve, means for connecting the driving sleeve to the drive shaft for rotation therewith, a driven clutch'element telescopically disposed with respect to the driving sleeve, a radially inwardly disposed flange on the hammer for abutment with the end of the driving element, interfitting means on the flange and driven clutch element for transmitting driving force from the clutch to the hammer, axially opposed. and substantially identical helical surfaces on the clutch driving sleeve and driven element, a plurality of balls interposed between the opposed surfaces for the transmission of driving forcetherebetween, an axially fixed abutment, and resilient means compressed between the axially fixed abutment and the flange on the hammer to urge the flange and abutting driven element toward the driving sleeve.

8. In a rotary impact tool, a rotatably supported anvil, a hollow cylindrical hammer having a portion normally aligned for engagement with the anvil, said anvil and hammer being axially reciprocable relative to one another for moving said portion of the hammer and the anvil from and to alignment with one another, a drive shaft, and torque responsive clutch means disposed within the hammer for providing a disengageable driving connection between the drive shaft and the hammer, said clutch means comprising a driving sleeve, means for connecting the driving sleeve to the drive shaft for rotation therewith, a driven clutch element within the hammer, interfitting means connecting the hammer for rotation with the driven element, axially opposed and substantially identical helical surfaces on the clutch driving sleeve and driven elements, a plurality of balls interposed between the opposed surfaces for the transmission of driving force therebetween, a helical spring urging the clutch driving sleeve and driven element together, and means for limiting the compressed height of the spring.

9. In a rotary impact tool, a rotatably supported anvil, a hollow cylindrical hammer having a portion normally aligned for engagement with the anvil, said anvil and hammer being axially reciprocable relative to one another for moving said portion of the hammer and the anvil from and to positions of alignment, a drive shaft, and torque responsive clutch means disposed within the hammer for providing a disengageable driving connection between the drive shaft to the hammer, said clutch means comprising a driving sleeve, means for connecting the driving sleeve to the drive shaft for rotation therewith, a driven clutch element telescopically disposed with respect to the driving sleeve, a radially inwardly disposed flange on the hammer and abutting on the end of the driven element, interfitting means on the flange and driven element for transmitting driving force from the clutch to the hammer, axially opposed and substantially identical helical surfaces on the clutch driving sleeve and driven element, a plurality of balls interposed between the opposed surfaces for transmitting driving force therebetween, an axially fixed abutment, a helical spring compressed between the axially fixed abutment and the flange on the hammer to urge the flange and abutting driven element toward the driving sleeve, and a sleeve surrounding the spring and disposed between the axially fixed abutment and the flange on the hammer and having an axial length substantially equal to the minimum allowable compressed height of the spring.

10. In a rotary impact tool, a rotatably supported anvil, a hollow cylindrical hammer having a portion normally aligned for engagement with the anvil, said anvil and hammer being axially reciprocable relative to one another for movements of said portions of the hammer from and to positions of alignment with the anvil, a drive shaft, and torque responsive clutch means disposed within the hammer for providing a disengageable driving connection between the drive shaft to the hammer, said clutch means comprising a driving sleeve, means for connecting the driving sleeve to the drive shaft for rotation therewith, a driven clutch element telescopically disposed with respect to the driving sleeve, a radially inwardly disposed flange on the hammer for abutment with the end of the driven element, interfitting means on the flange and driven element for transmitting driving force from the clutch to the hammer, two pairs of substantially parallel and helical radially disposed surfaces, one of each pair of surfaces being on the driving sleeve and the other on the driven clutch element, each pair being curved in the opposite direction from the other pair, and the ends of the pairs being joined to comprise continuous surfaces on the driving sleeve and driven clutch element, a plurality of balls interposed between the opposed surfaces for the transmission of driving force therebetween, an axially fixed abutment, a helical spring compressed between the axially fixed abutment and the flange on the hammer to urge the flange and abutting driven element toward the driving sleeve, and a sleeve surrounding the spring and disposed between the axially fixed abutment and the flange on the hammer and having an axial length substantially equal to the minimum allowable compressed height of the spring.

11. A rotary impact tool as defined in claim 10, and wherein the driving sleeve has a peripheral groove adjacent the helical surfaces thereon for receiving said balls, and wherein the hammer extends over the balls and serves to retain them in the groove while said surfaces are separated as a result of relative rotation therebetween.

12. in a rotary impact tool, a rotatably supported anvil, a hollow cylindrical hammer having portions adapted to engage the anvil, said anvil and hammer being coaxial and relatively reciprocable axially of the anvil, a drive shaft, and torque responsive clutch means disposed within the hammer and adapted to effect connection of the drive shaft to the hammer to drive said hammer, said clutch means comprising a driving sleeve, means connecting the driving sleeve to the drive shaft for rotation therewith, a driven clutch element within the hammer, interfitting means for connecting the hammer for rotation with the driven element, axially opposed and substantially identical helical surfaces on the clutch driving sleeve and driven element, a plurality of balls interposed between the opposed surfaces and adapted to transmit a driving force therebetween, and resilient means urging the clutch driving sleeve and driven element together.

No references cited. 

